pcv valve

Your not wrong there Bruce, been looking for ages for the fill pipe n cap. Would make it so much easyer for oil filling on my 42 pickup,up near the front, where I can reach without laying on the fender. I'm a short arse, and it's a long way back.
Martin.
 
V8 Bob said:
Why is it not worth it when the environment, oil and internal engine stays much cleaner with a properly operating PCV system? I, along with many others, know first hand adding a PCV is well worth it, fact not opinion. :)
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A well designed PCV valve system is a great thing, no doubt. I am glad that the modern cookie cutter car that I drive through city traffic on a daily basis has a good PCV system.

I don't drive my old Fords daily anymore. My flatheads (and 215 OHV six) run well. I am not bothered with blow by fumes when driving. If I had a car that smoked that badly, I'd rebuild the engine. If you let your engine reach a good operating temperature (typically 180 F water temperature) and run modern detergent oils then sludge and acid build up are not a big problem. Keeping your oil changed and your engine in good tune will do more than adding a PCV valve to a carburetor system not designed for one. Think about it, if you run rich you are going to use more gasoline, a small fraction of which will end up in the crankcase. I'd rather have my engine in proper tune.

Another thing that bothers me is adding a PCV suction to the wrong point in an engine. A properly done PCV draws air through a filter, into the crankcase, then into the intake. Many PCV installations on a flathead (almost all of them on 59 series and older engines) draw air in through the unfiltered passage that used to be the crankcase vent outlet. This draws road grime and dust into your engine, adding contamination. This is exactly the opposite of what you are trying to accomplish when adding a PCV. The only easy way that I have thought of to properly to add PCV to a flathead V8 would be: start with an 8BA; remove the road draft tube and replace it with a PCV valve; then run the output of the PCV into the air cleaner, not the carburetor. Before WWII John Deere started venting their crankcase into the air intake before the carburetor.

I have torn down a couple early Ford engines after driving them daily. I found no evidence of moisture or water damage to the internal parts. Adding a PCV to an early Ford solves problems I don't have, and adds problems I don't want to have to solve. That is my opinion.

My hat is off to anyone willing to read all of this post (but you did ask...).
 
Ford blocked the early type pan vent and drew the fumes out at the TOP of that stack rather than the bottom, via fitting through side of generator perch. Air IN came in through the oil filler cap, as on the non-positive vent system, but they used a cap with a much more elaborate filter in place of the brillo pad.
 
trvguy said:
Some time back i wrote about putting a pcv valve on a ford flathead. I've gotten some answers but not about a 1948 Merc engine. Is there a road draft tube on this engine? How can i hook up a pcv valve on this engine???
HELP.
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I all honesty this is one of those subjects were its rare for even two people to fully agree on any aspect of it.
BTW
Iv successfully built a (hidden) PVC system that works perfectly
 
Old Ford Addict said:
I all honesty this is one of those subjects were its rare for even two people to fully agree on any aspect of it.
BTW
Iv successfully built a (hidden) PVC system that works perfectly
Click to expand...

I built one for a pre-8BA Thickstun that tapped into both plenums (underside of manifold). I made a vent cap with filtering material.
 
Bruce Lancaster said:
The extra port on manifold, I think, is a big one (3/8 pipe??) with two tiny drillings into the actual passages...is that what you have?? That would be a port for truck vac brakes, and a logical connection. I've seen those plugged on some manifolds, on others just a flat area to allow the drilling.
Mine matches drawings that are in 1943 editions of Canadian military Ford manuals, with the plate under carb hooked to the line from PCV mounted vertically below front of carb and connected to the fitting on side of gen stand.
I discovered recently that WWII Jeeps used a VERY similar PCV that is now available in repro. I'm going to get around to buying one to compare.
My setup, the most complete I have found, is on the same Canadian aluminum manifold with 3-4 bolt capable carb stand. I think the 4 bolt may have been for some British Solex rig, pure guesswork on my part. There was considerable effort to keep spare part interchangeability between Canadian, US, and British flatheads.
The plate is a thin die cast piece that lives below carb, and at the front it has a threaded hole for adaptor to the steel line. This fairly large opening dead ends and is drilled with two little holes Veed out to meet both sides of intake.
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Post war Jeeps also used a PCV, not sure if it is the same as you are talking about.
 
1952henry said:
I built one for a pre-8BA Thickstun that tapped into both plenums (underside of manifold). I made a vent cap with filtering material.
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Exactly what I did on this Edelbrock Super
Photo is before I put the 5/16 bore valve were the barbed fitting is

73442966.jpg
 
Mr 38 coupe, the type I spoke of and me and Bruce were discussing pulls in via the filtered oil filler cap. Not through the pan breather. I would never suggest pulling in air via the breather down on the pan, that is a stupid idea, and can't understand anybody thinking it's a good idea, as you said, pulling in air from the dirty road surface. I've been told "I don't drive on dirt roads, so what's the problem?" I say get a totsie roll unwrap it roll it along your "clean dirt free road" for a couple of miles, then eat it. Feel gritty?
I'm not poo pooing Ross's test, just that many many folk are using pcv setups and all's well. And done properly, they will make a difference in the cleanliness of the inside of the engine. I've tugged a good few old dormant flatheads apart, and can tell you that the two with the pcv setups were a lot less tar filled in the valve chamber than the ones without.
Martin.
 
The pan breather is an EXIT. It isn't really well placed to remain the exit in a PCV setup, so the factory just capped it off (no bump at all on some pans, slot not cut on others) and drew from the other end of the forward vent stack up at the top. The inlet for air remained the same, but got a much more serious filter from the factory.
On getting it workable...Ford managed, presumably by careful sizing of the smallest apertures in flow, and everyone got them working fine in the early 1960's.
The various carters and Rochesters in use in '63 or so when PCV went to common use used idle systems just as primitive as our Ford 94's and Strombergs. Yes, a PCV is an unmetered leak, but if it is small it gets covered by minor enrichment at idle screws. According to some reading I have done it is much less of a leanerouter than might be supposed...the normal levels of blowby and oil fumes actually make it a source of burnable hydrocarbons*.
Along with thermostats getting water and other vapors outta there remove most of the sources of sludge.

*Which gets back to one of the reasons PCV was adopted as an anti-smog measure...
Ford wanted it in WWII for other reasons, of course.
 
I didn't actually say in my bit that the pan vent is an exit, I should have, just so it's clear as can be. It should read " I would never suggest pulling in air via the EXIT breather down on the pan, that is a stupid idea, and can't understand anybody thinking it's a good idea, as you said, pulling in air from the dirty road surface"
Making it clear that I'm singing from the same hymn sheet as Bruce.
I like the word "leanerouter"
I believe the cap that is normal the oil fill on the fuel pump stand, is replaced with a miniature oil bath filter when the pcv was used. Van you confirm this Bruce?
Martin.
 
Sometimes ignorance is bliss...I am running a pair of 94's with a PVC Valve and all seems fine..
 
I've only seen pictures of the complete rig, I only have the top end PCV to carb parts, but the manual show an oil bath that looks like a half-scale version of a typical Ford car oil bath air cleaner in place of the can full of brillo.
The carbs generally had the big accessory oil bath that went on a cylinder head.
Two versions of the PCV pan have been posted on here...one is the normal pan with the hole in the draft bump left uncut, the other is a pan made with the bump totally eliminated and just a flat area of pan flange there to close off the hole.
I wish I knew the story of how a Canadian built WWII military PCV setup landed in a New Jersey fleamarket pretty much intact.
The Canadian heads and Manifolds were briefly easy to get here in the '70's when Joblot acquired vast quantities of WWII surplus Fordage from Canadian, Indian, Swiss, and British stocks...along with all the 7RA aluminum heads left on the planet.
 
I have not had the benefit of seeing a WWII PCV equipped engine, it sounds like a good setup. I haven't seen anyone duplicate that on a street driven engine. For my driving habits (driving long distance at hiway speeds) getting the engine to run well on today's alcohol filled gasoline is much more important that sludge build up.

I remember reading an article in the V8 Times advocating drilling and tapping the bottom of your pre-8BA intake and threading a PCV valve directly into the manifold. No directions were given relative to the pan breather, balancing the two halves of the intake, or anything. It looked like a horrible idea to me.

Does anyone else have fuel air meter results for a flathead equipped with both an early carb (or carbs) and a PCV?

What fuel air results have been had with modern four barrels on flatheads with PCVs? Someone has had to have investigated this.
 
Mr 38 coupe, for modern 4bbl and pcv with air/ fuel ratios and lots of on street testing, Richard in Florida has this setup, if I recall correctly. He has an Edelbrock carb and L100 cam,
I have the WW2 pcv rig on my truck with a 94, poor thing is not road ready yet but hopefully soon will be, been saying that for a while but money and luck keeps getting in the way.
This truck is beeing built for economy and testing parts, he already tests every carb and converted distributors I build. Has a Merc overdrive trans in him to help with the economy.
When he's on the road, he will most likely be in a constant test mode.
Martin.
 
I'm with 38Coupe on this one. I cannot see that the amount of clean air drawn in with a PCV valve, which is quite a restricted feed, is going to make much difference to the state of the inside of your block. There is plenty of turn-over of the gases inside the engine...just try putting your hand over the breather and revving the motor. It comes in through the carb and blows past the pistons, into the crankcase and straight out the breather. I didn't like the smell so capped off the breather and fed the result back into the air-cleaner...works fine.
 
I measured the holes in the inlet manifold that my pcv type engines breath through (truck air assisted brake port) the two holes are 0.250" diameter. I pulled the pcv off and played sucking and blowing with it, the actual valve does create quite a restriction itself. Although the plumbing is big, there are fairly small clearances in side.

Someone said earlier that in theory the pcv should only open at low load cruise. This is incorrect, most are open all the time, low load (high vacuum) has them in a minimal open position (less flow), high load foot to the floor stuff (low vacuum) opens them more. This is how the Donaldson crankcase ventilator works, and the three I have on the shelf from small four cylinder stuff.
I don't think a pcv will work feeding in side the air cleaner. There not designed for this. There are some factory installations that run a pcv and have a pipe into the air cleaner, but these use the air cleaner for supply of filtered air to the crankcase. An early factory 302 setup works thus, pipe from one valve cover to the air cleaner, other valve cover has the pcv and is plumbed to the carb base (manifold vacuum).
Air is drawn in from the air cleaner, through that pipe to the valve cover. This air travels down through the head into the crankcase and valley, then up through the other side of the engine, through the head, into the valve cover, into the pcv and lastly through its pipe and into the inlet manifold. What I don't personally like about this setup, is on worn engines the oil laden fumes from blowbye at high vacuum (idle and when the pcv is in its most closed position) travel up the air cleaner to valve cover pipe, and cover the inside of the air cleaner and the inside of the carb with oily slime. And can muck up the air bleads and much more tiny things in side the carb.
Sorry for the length, I feel relevant.
Martin.
 
scooder said:
Someone said earlier that in theory the pcv should only open at low load cruise. This is incorrect, most are open all the time, low load (high vacuum) has them in a minimal open position (less flow), high load foot to the floor stuff (low vacuum) opens them more. .
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Sorry, I should have been more specific. The valves are nearly closed at high vacuum and most open at medium cruise. At low vacuum (full throttle) the valves may close completely if crankcase pressure becomes positive by blowby.
 
I cannot find much of my Canadian PCV setup...obviously, I carefully put it some place safe and accessible! Manifold is stripped, PCV, tubing, and carb plate are in hiding.
The drillings from fitting cavity in carb plate to manifold riser passages below carb are for sure smaller than the holes in you manifold. I can only guess until I re-locate the blasted thing, but my memory says they must be close to .060. Definitely down in the itty-bitty range...
 
If you all had ever seen what happens when blowbye is ignited in a confined place (like in a motor) you’d know what the pcv valves #1 job is …. it’s a check valve
 
Old Ford Addict said:
If you all had ever seen what happens when blowbye is ignited in a confined place (like in a motor) you’d know what the pcv valves #1 job is …. it’s a check valve
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That's right, but venting your crank to your intake manifold is probably the only way a fire could light up your crankcase in the first place!
 
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